Evaporative cooler

ABSTRACT

An evaporative cooler that includes a frame, a plurality of pads attached to the frame so that the pads substantially enclose an air space to be cooled, a water delivery device positioned at or near the top of the pads to wet the pads, a plurality of drain pans positioned at or near the bottom of the pads to collect water from the pads, and a fan to draw air through the wetted pads, thereby cooling the air by evaporation.

FIELD OF THE INVENTION

The present invention relates generally to evaporative coolers usingcooling pads. More particularly, the present invention relates toevaporative coolers having discrete cooling pads that can be removed andreplaced individually.

BACKGROUND AND SUMMARY OF THE INVENTION

Air cooled heat exchangers are commonly used in a wide variety ofindustries. As the name implies, heat exchangers are devices where twomoving fluid streams exchange heat. In an air cooled heat exchanger, afluid that is circulated through tubes may be cooled by forcingrelatively cool ambient air to flow over the exterior of the tubes. Asthe ambient air passes over the exterior of the tubes, it absorbs heatfrom the fluid within the tubes, thereby cooling the fluid. As usedherein, the term tubes refers to any mechanism for conveying fluidthrough a heat exchanger, including pipes of any shape, pressurevessels, etc. The lower the temperature of the ambient air, the greateris its capacity to absorb heat. Thus, air cooled heat exchangers aremost effective where the ambient air used to cool is at a lowtemperature.

It stands to reason, therefore, that the performance of air cooled heatexchangers suffers when the heat exchanger is operated in a hot climateor during the summer months when the temperature of the ambient air isrelatively high. Under such conditions, air cooled heat exchangerperformance deteriorates rapidly. As a result, it is necessary topre-cool the ambient air prior to its introduction to the heatexchanger.

There are numerous methods and devices for cooling air prior to itsinitiation to a heat exchanger, such as, for example, subjecting the airto a refrigeration process or an evaporative cooling process. Coolingsystems that rely on a refrigeration cycle have disadvantages, includingthe fact that they typically have high initial and operating costs.Where the climate permits (i.e., where the climate is hot and dry),evaporative cooling may provide a better solution.

Evaporative cooling relies on one simple principle: As water evaporates,heat is absorbed from the surrounding air. As a result, the air iscooled during the process. An evaporative cooler preferably includesporous cooling pads that substantially surround an enclosed space thatincludes a fan. Moisture is applied to the pads, typically either bydripping water into the top end of the pads, or by spraying the padswith a mister. The fan is arranged to pull ambient air through the padsand into the enclosed space. As the air passes through the pads, themoving air evaporates the water in the pads. This evaporation cools theair as it enters the enclosed space. The fan then expels the cooled airfrom the enclosed space through an outlet.

One advantage to an evaporative cooler such as that just described isthat the water supplied to the cooler does not need to be clean. Ifwater that has impurities or contaminates is provided to the coolingpads, the air passing through the pads will still evaporate the waterand be cooled. The contaminates will simply stay in the pads. Thus, intheory evaporative coolers are well suited to use, for example, in heavyapplications such as oil production, where the water available may becontaminated with oil.

The practical use of evaporative coolers in industrial or other heavyapplications is limited, however, by the size of the coolers required.Some applications require such a large amount of air to be cooled thatevaporative coolers having very large air intake surface areas would berequired to meet the demand. For example, a typical cooler bank at anoil production facility might require an air intake surface area ofaround 50,000 square feet or more. The size of the cooling pads thatwould be needed on a conventional evaporative cooler of that size wouldbe impractical to manufacture, maintain, or replace.

In one embodiment, the present invention provides an evaporative coolerthat includes a frame, a plurality of pads attached to the frame so thatthe pads substantially enclose an air space to be cooled, a waterdelivery device positioned at or near the top of the pads to wet thepads, a plurality of drain pans positioned at or near the bottom of thepads to collect water from the pads, and a fan to draw air through thewetted pads, thereby cooling the air by evaporation.

In another embodiment, the present invention may also provide an aircooled heat exchanger that includes cooling tubes containing a fluid tobe cooled, and a supply of air that flows over the cooling tubes, theair having a lower temperature than the fluid to be cooled so that theair absorbs heat from the fluid, thereby cooling the fluid, and whereinat least a portion of the supply of air is provided by an evaporativeair cooler. The evaporative air cooler includes a frame having aplurality of vertical open sides, wherein each side includes two or morestacked cooling sections, a plurality of pads attached to the frame sothat the pads enclose the open sides of the frame, each padcorresponding to a cooling section, a plurality of water pipes attachedto the cooler and positioned at the top of each cooling section adjacentthe top of the pads, the water pipes having apertures arranged to allowwater to exit the pipes and wet the pads, a plurality of drain panspositioned at the bottom of each cooling section adjacent the bottom ofthe pads to collect any water that drips from the pads, and a fanconfigured to draw air through the wetted pads, thereby cooling the airby evaporation, and provide the cooled air to the heat exchanger.

In one embodiment, the present invention also provides a method ofcooling air, the method including the steps of providing a plurality ofcooling pads stacked one on top of the other and substantially enclosingan air space to be cooled, wetting the cooling pads at an upper portionthereof, and pulling ambient air through the wetted cooling pads andinto the air space to be cooled.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the subject matter of the presentinvention and the various advantages thereof can be realized byreference to the following detailed description in which reference ismade to the accompanying drawings in which:

FIG. 1 is a schematic perspective view of a cooler;

FIG. 2 is a perspective view of the frame of a cooler;

FIG. 3 is a schematic cross-sectional view of the cooling pads, waterdelivery pipes, and drain pans of a cooler taken along line 3-3 of FIG.1;

FIG. 4A is a perspective view of an intermediate drain pan to bepositioned between two adjacent stacked cooling pads;

FIG. 4B is a perspective view of a bottom drain pan to be positionedbelow the bottom most cooling pad;

FIG. 5A is a perspective view of water delivery pipe corresponding toone layer of cooling pads; and

FIG. 5B is a perspective view of a portion of the water delivery pipe ofFIG. 5A showing the perforations through which water is delivered.

DETAILED DESCRIPTION OF THE INVENTION

The foregoing aspects, features, and advantages of the present inventionwill be further appreciated when considered with reference to thefollowing description of preferred embodiments and accompanyingdrawings, wherein like reference numerals represent like elements. Indescribing embodiments of the invention illustrated in the appendeddrawings, specific terminology will be used for the sake of clarity.However, the invention is not intended to be limited to the specificterms used, and it is to be understood that each specific term mayinclude equivalents that operate in a similar manner to accomplish asimilar purpose.

Referring now to the drawings, FIG. 1 shows a schematic perspective viewof a cooler 10 according to one embodiment of the present invention. Thecooler includes a face portion 16 having at least one fan located in anopening 12. As shown in FIG. 1, the face portion 16 may include aplurality of fans, although such is not necessary. The number of fanswill depend on the size of the cooler, among other factors. The sides ofthe cooler 10 are substantially enclosed with cooling pads 14. Thecooling pads 14 are porous, thereby allowing for the passage of airthrough the pads 14. In practice, water is introduced to the pads 14 ata top portion thereof and descends through the pads until the pads arewet. The fans are configured to draw air from the ambient environment tothe inside of the cooler through the pads 14. As the air passes throughthe wet pads, heat from the air evaporates the water in the pads,thereby cooling the air. The cooled air may then be propelled frominside the cooler 10 through outlets on the face portion by the fans.

Each side of the cooler may preferably include a plurality of discretepads that may be individually removed for cleaning or replacement. Oneadvantage to such a configuration is that individual pads are smallerand may be removed and replaced more easily. As the pads become worn outor saturated with contaminates from water that has been evaporated, suchremoval of the pads for cleaning or replacement may be needed. Aconfiguration with smaller pads, such as that shown in FIG. 1, allowsfor such removal and replacement of pads with minimal interruption tothe operation of the cooler 10. For example, the pads may be removed andreplaced while the cooler is running, thereby avoiding potentiallycostly downtime.

In one embodiment, the cooler 10 may include, a plurality of pads 14that lie horizontally and are stacked one on top of the other as shownin FIG. 1. Alternatively, the pads may be angled with respect to theface of the cooler, or positioned vertically side by side. If the padsare angled, they may be positioned so that the centerline of each padlies at a 45 degree angle to the horizontal face of the cooler.Alternatively, the pads may be angled less than 45 degrees to thehorizontal face, such as, for example, around 10, 20, 30, or 40 degrees,or more than 45 degrees, such as around 50, 60, 70, or 80 degrees. Theorientation and arrangement of the pads is not critical to theinvention.

Any pad that holds water, and allows air to pass through the pad toevaporate the water, may be used in the present invention. The materialsthat make up the pads and the manner of construction of the pads are notcritical. One example of a cooling pad that may be used in oneembodiment consists of impregnated and corrugated cellulose paper sheetswith different flute angles, one steep (e.g., about 60 degrees) and oneshallow (e.g., about 30 degrees), that have been bonded together. Thisparticular design yields a cooling pad with a high evaporationefficiency while still operating with a very low pressure drop. Inaddition, such a design keeps scaling to a minimum because water isnaturally directed to the air inlet side of the pad, where most of theevaporation takes place. In addition, the impregnation procedure for thecellulose paper ensures a strong self-supporting pad, with highabsorbance, which is protected against decomposition and rotting.Alternatively, pads may be constructed of other materials, such as, forexample, excelsior (wood wool), plastics, and melamine paper.

Referring now to FIG. 2, there is shown a perspective view of a cooler10 according to one possible embodiment of the present invention withthe pads removed. As can be seen, the frame 18 of the cooler 10 includeslegs 20 that may be positioned at corners of the cooler 10 such that thearea between the legs 20 forms the sides of the cooler. The legs 20 offrame 18 may serve to support the stacked pads 14 (shown in FIG. 1). Theembodiment of FIG. 2 further shows an air intake 22 inside the cooler 10that has at least one fan (not shown) positioned therein. In operation,the fan is arranged to pull air into the air intake 22 and expel itthrough the face portion 16 of the cooler. When the pads 14 are inplace, such as shown, for example, in FIG. 1, air is pulled through thepads 14 toward the air intake 22.

The frame may be made of any suitable material, which material may varydepending on the requirements of the cooling system, the environment inwhich the cooling system is operated, and many other factors. In oneembodiment, the frame may be constructed of steel. The frame may beconstructed so that the cooler is positioned above the ground. Forexample, in one embodiment, the cooler may be 30 feet or more above theground. In other embodiments, the cooler may be 10, 15, 20, or 25 feetor more off the ground. The placement of the cooler will depend on theconditions at the site where the cooler is to be installed and thearrangement of components to which the cooler is to be connected, suchas a heat exchanger. The size and configuration of the frame will varydepending on factors such as the size of the cooler and the position ofthe cooler above the ground. For example, a larger cooler will require alarger, more heavy duty frame. Similarly, a cooler that is 30 feet ormore above the ground will require a frame structure capable of liftingthe cooler to that height while still providing a stable foundation forthe cooler to rest on. Accordingly, the size, configuration, andcomposition of the frame are not critical to the invention.

FIG. 3 shows a cross-sectional view of the cooling pads 14, as well aswater delivery pipes 24, intermediate drain pans 26, and bottom drainpan 28 taken along line 3-3 of FIG. 1. As discussed above, in practicewater is introduced to the pads 14 at a top portion thereof and descendsthrough the pads until the pads are wet. To accomplish this, water isdelivered to the top of each pad by water delivery pipes 24. The waterdelivery pipes 24 have apertures 30 (shown in FIG. 5B) that allow waterrunning through the pipes to discharge directly onto the pads 14 at aninterface 32 between the water pipes 24 and the pads 14. As discussedabove, the pads 14 are porous and are typically constructed of aplurality of corrugated cellulose paper sheets that are bonded together,although any suitable material may be used. As the water is delivered tothe top of each pad 14, it travels downward through the porous pad untilsubstantially all of the pad becomes wet. Excess water drains from thebottom of the pad.

At the bottom of each pad there is preferably a drain pan 26, 28. Allbut the bottom most pads are positioned above intermediate drain pans26. The intermediate drain pans 26 are configured to collect water thatdrains from the bottom of the pad directly above each intermediate drainpan 26, and deliver that water to the top of the next lower pad. Thebottom drain pan 28 is positioned below the bottom most pad. The bottomdrain pan 28 may be shaped differently from the intermediate drain pans26 because the function of the bottom drain pan 28 is not to deliverwater to a lower pad, but rather to collect water for reuse either inthe cooler or elsewhere, or for disposal according to known methods. Amore detailed explanation of the shape and function of the intermediateand bottom drain pans 26, 28 is written below with respect to FIGS. 4Aand 4B.

In operation, the water delivery pipes 24 deliver water to the tops ofpads 14 and the water percolates down through the pads 14 until the padsare wetted. Ambient air is pulled through the pads, as discussed above,by fans 12 into an air intake inside the cooler 10. The direction ofmotion of the air through the pads is indicated in FIG. 3 by arrows A.As the air passes through the wet pads, it evaporates the water in thepads. The energy required for such evaporation is pulled from thepassing air in the form of latent heat. Thus, as the air passes throughthe pads and the water evaporates, the air is cooled. Because of thisevaporation, much of the water that is provided to the top of the padsby the water delivery pipes 24 never reaches the bottom of the pads. Thewater that does reach the bottom of the pads, however, drains into theintermediate drain pans 26 and is channeled to the top portion of thenext lower pad. Any water that reaches the bottom of the bottom most paddrains into the bottom drain pan 28 where it may be recycled for reuse,in which case it is reintroduced to the water delivery pipe system, orit may be disposed of according to conventional methods.

There is shown in FIGS. 4A and 4B drain pans according to an embodimentof the present invention. FIG. 4A shows an intermediate drain pan 26that may be sloped from a raised first end 34 to a depressed second end36. The sides of the drain pan 26 are raised and enclose a trough 38 forcatching water. When in use, a pad 14 is positioned so that its bottomportion drains excess water into the trough 38. If the drain pan 26 issloped, the water runs to the depressed second end 36 thereof. At thedepressed second end 36 there is an aperture (not shown) or other outletthat permits the water to exit the trough 38 of the drain pan 26, whereit enters the top of the next lower pad (see FIG. 3). If the drain panis not sloped, the aperture or other outlet may be positioned anywherein the bottom of the drain pan.

FIG. 4B shows a bottom drain pan 28 according to an embodiment of thepresent invention. Similar to the intermediate drain pan 26, the bottomdrain pan 28 may have a raised first end 40 and a depressed second end42. The bottom drain pan also has raised sides that define a trough 44.In the embodiment shown, the bottom drain pan may have a trough 44 thatis elongated compared to the troughs 38 of the intermediate drain pans26. In addition, the slope of the bottom drain pan 28 may change at aslope transition place 46, although the length of the trough and theexact slope of the drain pan are not critical to the design of thecooler and may vary depending on the needs and configuration of aparticular cooler arrangement. In addition, there is at least oneaperture 48, or other outlet, at or near the depressed second end 42 ofthe bottom drain pan 28 to allow water to exit the drain pan. Afterexiting the drain pan, the water may be recycled for reuse in thecooler, or it may be disposed of according to known conventionalmethods.

The drain pans 26, 28 may be constructed of any suitable material, suchas, for example, metal or plastic. Because the function of drain pans26, 28 is to collect water, they are preferably constructed of amaterial that will not be adversely affected by contact with water.Furthermore, the shape and configuration of the drain pans in thedrawings is merely a representation of one particular embodiment. Theshape of the drain pans is not critical to the invention and any shapethe allows the drain pans to carry out their intended functions iscontemplated.

Referring now to FIG. 5A, there is shown a water distribution pipe 24according to one possible embodiment of the present invention. The waterdistribution pipe is preferably positioned around the sides of thecooler 10 so that the pipes are adjacent the top of a row of pads (see,e.g., FIG. 3). There is a water inlet 50 through which water may besupplied to the delivery pipes 24. The water inlet may be configured toconnect to, for example, a water hose that is connected to a source ofwater. The water delivery pipe 24 shown in FIG. 5A is only one portionof the water delivery system that may be employed in a single cooler.For example, the water delivery pipe 24 of FIG. 5A corresponds to asingle pipe capable of delivering water to a single layer of pads.However, As shown, in FIG. 3, certain embodiments of the inventioncontemplate the use of multiple layers of pads, with each layer havingits own water delivery pipe 24 similar to that shown in FIG. 5A. Ofcoarse, more than one pipe may be used to deliver water to each layer ofpads. Preferably, for purposes of simplicity, each layer is connected toa single common water source. This is not necessary, however, anddifferent water delivery pipes 24 may be connected to different sourcesof water. FIG. 5B shows a magnified view of a portion of a waterdelivery pipe 24 showing apertures 30 through which water may bedischarged from the water delivery pipe 24 to a corresponding pad.

The arrangement and construction of the water delivery pipes is notcritical to the present invention, and the pipes may be constructed ofany material suitable for carrying water. For example, the pipes may beconstructed of steel or plastic. In addition, while the water may bedischarged from the pipes and onto the pads through apertures in thepipes, as discussed above, this configuration is not critical. Othermechanisms for dispersing water from the pipes to the pads may beemployed as well. For example, in one embodiment the pipes may be fittedwith nozzles that drip or spray the water onto the pads in the form of amist.

An advantage of the present invention is that the water used in thecooler need not be clean, although clean water can be used if desired.In one embodiment, the water used in the cooler may be produced waterthat has been extracted with oil during an oil production process. Insuch a case, the water may be contaminated with up to 2 percent oil, andsometimes as high as 3 percent or more. Although such produced water maybe filtered prior to use in the cooler, this is not necessary. In somecases, the cooler may be connected directly to an oil producing facilitywith produced water being fed directly to the cooler.

The reason that the cooler of the present invention can be used withcontaminated water is because as the water evaporates from the pads, anycontaminates within the water will remain in the pads. The consequenceof this is that over time, the contaminates within the pads willincrease until air flow through the pads is restricted. However, asdiscussed above, the design of the cooler allows for individual pads tobe removed as needed for cleaning or replacement, thereby allowingcontinued use of the cooler despite the buildup of contaminates from thewater. This provides a benefit over coolers that need clean water tooperate.

To better understand the cooling potential of an evaporative cooler, thefollowing example may be considered. In the example, a cooler having awidth of 112 feet, a length of 62 feet, and a height of 20 feet isprovided. This sides of the cooler are enclosed with cooling pads havinga thickness of 2 feet. The pads are provided about 850 gallons of waterper minute distributed evenly throughout the pads. The ambient airentering the pads has a dry bulb temperature of 104 degrees Fahrenheit,and a wet bulb temperature of 71 degrees Fahrenheit. After passingthrough the pads and evaporating the water in the pads, the cooled airwill have a temperature of 90 degrees Fahrenheit.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention.

What is claimed is:
 1. An evaporative cooler, comprising: a frame; aplurality of pads attached to the frame so that the pads substantiallyenclose an air space to be cooled; a water delivery device positioned ator near the top of the pads to wet the pads; a plurality of drain panspositioned at or near the bottom of the pads to collect water from thepads; and a fan to draw air through the wetted pads, thereby cooling theair by evaporation.
 2. The evaporative cooler of claim 1, wherein thepads include a bottom pad and intermediate pads positioned above thebottom pad.
 3. The evaporative cooler of claim 2, wherein the drain pansassociated with the intermediate pads are configured to deliver thecollected water to the lower pads.
 4. The evaporative cooler of claim 1,wherein the cooler is configured to recycle the collected water forreuse.
 5. The evaporative cooler of claim 1, wherein the water iscomprises one or more contaminates.
 6. The evaporative cooler of claim5, wherein the one or more contaminates includes oil.
 7. The evaporativecooler of claim 1, wherein the frame has a horizontal face, and the fanis configured to expel the cooled air through the face and out of thecooler.
 8. An air cooling bank comprising a plurality of evaporativecoolers wherein one or more coolers is as claimed in claim 1, whereinthe evaporative coolers are connected together and configured to runsimultaneously, thereby increasing the amount of air cooled.
 9. Theevaporative cooler of claim 1, wherein the water delivery device is aplurality of pipes positioned adjacent the top of the pads.
 10. Theevaporative cooler of claim 9, wherein the pipes have aperturesconfigured to release water from the pipes onto the pads.
 11. A methodof cooling air, comprising: providing a plurality of cooling padsstacked one on top of the other and substantially enclosing an air spaceto be cooled; wetting the cooling pads at an upper portion thereof;pulling ambient air through the wetted cooling pads and into the airspace to be cooled.
 12. The method of claim 11, wherein the waterapplied to the cooling pads comprises one or more contaminates.
 13. Themethod of claim 12, wherein the one or more contaminates includes oil.14. The method of claim 11, further comprising collecting excess waterfor reuse after it passes through the cooling pads.
 15. An air cooledheat exchanger, comprising: cooling tubes containing a fluid to becooled; and a supply of air that flows over the cooling tubes, the airhaving a lower temperature than the fluid to be cooled so that the airabsorbs heat from the fluid, thereby cooling the fluid; wherein at leasta portion of the supply of air is provided by an evaporative air cooler,the evaporative air cooler comprising: a frame having a plurality ofvertical sides, wherein each side includes two or more cooling sections;a plurality of pads attached to the frame so that the pads enclose thesides of the frame, each pad corresponding to a cooling section; aplurality of water pipes attached to the cooler and positioned at thetop of each cooling section adjacent the top of the pads, the waterpipes having apertures arranged to allow water to exit the pipes and wetthe pads; a plurality of drain pans positioned at the bottom of eachcooling section adjacent the bottom of the pads to collect any waterthat drips from the pads; and a fan configured to draw air through thewetted pads, thereby cooling the air by evaporation, and provide thecooled air to the heat exchanger.
 16. The evaporative cooler of claim15, wherein the cooler is configured to recycle the collected water forreuse.
 17. The evaporative cooler of claim 15, wherein the water iscomprises one or more contaminates.
 18. The evaporative cooler of claim17, wherein the one or more contaminates includes oil.
 19. An aircooling bank comprising a plurality of evaporative coolers wherein oneor more coolers is as claimed in claim 15, wherein the evaporativecoolers are connected together and configured to run simultaneously,thereby increasing the amount of air cooled.